Synthesis of 6-chloro and 6-fluoro-4-hydroxyl-2-quinolone and their azo disperse dyes

Article abstract of DOI:10.1016/j.cclet.2010.01.017

In this study, 6-chloro-4-hydroxy-2-quinolone and 6-flouro-4-hydroxy-2-quinolone were synthesized from corresponding dianilides. These compounds were coupled with some diazotized aromatic amines to give the corresponding azo disperse dyes. The structures

Full text of DOI:10.1016/j.cclet.2010.01.017

Available online at www.sciencedirect.com
Chinese Chemical Letters 21 (2010) 542–546
www.elsevier.com/locate/cclet
Synthesis of 6-chloro and 6-fluoro-4-hydroxyl-2-quinolone
and their azo disperse dyes
Enayat O’llah Moradi-e-Rufchahi
Department of Chemistry, Faculty of Science, Islamic Azad University, Lahijan Branch, Lahijan, Iran
Received 7 September 2009
Abstract
In this study, 6-chloro-4-hydroxy-2-quinolone and 6-flouro-4-hydroxy-2-quinolone were synthesized from corresponding
dianilides. These compounds were coupled with some diazotized aromatic amines to give the corresponding azo disperse dyes. The
1
structures of the quinolone derivatives and new azo dyes were confirmed by UV–vis, FT-IR, H NMR and elemental analysis.
# 2010 Enayat O’llah Moradi-e-Rufchahi. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
Keywords: Azo dyes; Hydroxy quinolone; Heterocyclic amines; Solvatochromism; Polyphosphoric acid; Heterocyclic dyes
It is well known that azo pigments are used in several technical fields, e.g. printing inks, paints [1–6] and the dyeing
of artificial fabrics [7–12]. The research on this class of dyes has made considerable progress in the last fifty decades.
Especially heterocyclic azo dyes have attracted considerable interest and have played an important role in the
development of the chemistry of dyes and dying process [13–17]. For example these classes of dyes have higher
tinctorial strength and give brighter hues than those derived from aniline-based diazo components and also provide a
pronounced bathochromic effect in comparison with the corresponding benzenoid compounds [18,19]. The
preparation of azo disperses dyes containing 4-hydroxy-2-quinolone as coupling component has been described in
literature [20]. Here, we report the synthesis of 6-chloro-4-hydroxyl-2-quinolone 1, 6-fluoro-4-hydroxy-2-quinolone 2
and using them as coupling components in reaction with diazotized 4-cyanoaniline, 4-nitroaniline, 2-
aminobenzothiazole and 8-aminoquinoline as diazo components. The visible absorption spectra of these dyes
were also discussed.
Once we irradiated a mixture of 4-chloro aniline and the other time 4-fluoro aniline and diethylmalonate (2:1 molar
ratio) under microwaves and prepared corresponding dimalonamide I and II in good yield. Heating N,N0-di(4-
chlorophenyl)malonamide and N,N0-di(4-fluorophenyl)malonamide in polyphosphoric acid (PPA) at 140–150 8C,
respectively afforded the 4-hydroxy-2-quinolon 1 and 6-fluoro-4-hydroxy-2-quinolone 2 (Scheme 1). The IR spectra
of compounds 1 and 2 showed strong broad absorption band at 3500–3150 cmꢀ1 for the hydroxy (OH) and amide
groups (NH). The absorption at 1654 cmꢀ1 for compound 1 and 1637 cmꢀ1 for compound 2 can be attributed to the
amide C O group. The 1H NMR spectrum (DMSO-d6) of compounds 1 and 2 exhibited a broad peak at 11.35 and
11.39 (br, 1H, NH), a singlet at 5.8 and 5.77 for the C C–H of pyridone ring, respectively.
E-mail address: moradierufchahi@gmail.com.
1001-8417/$ – see front matter # 2010 Enayat O’llah Moradi-e-Rufchahi. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
doi:10.1016/j.cclet.2010.01.017

E.O. Moradi-e-Rufchahi / Chinese Chemical Letters 21 (2010) 542–546
543
Scheme 1. Preparation of compounds 1 (X = Cl) and 2 (X = F).
1. Experimental
All the reagents and solvents were purchased from commercial suppliers. Melting points were determined on a
Barnstead Electrothermal 9100 melting point apparatus. Infrared spectra (in KBr pellets) were recorded on a
Shimadzu-8400 FT-IR spectrometer. 1H NMR spectra were recorded on a Bruker 300 MHz spectrometer in DMSO-d6
using TMS as an internal reference. Ultraviolet–visible (UV–vis) absorption spectra were recorded on a Cary UV–vis
double-beam spectrophotometer (Model 100). Microanalyses for C, H and N were performed on a PerkinElmer
2400(II) elemental analyzer.
4-Chloro or 4-fluoro aniline (10 mmol), diethyl malonate (5 mmol) were properly mixed in a 25 mL beaker and
properly mixed. The obtained mixture was irradiated in a microwave oven at the power of 320 W for 5 min. After
irradiation, the crude product was recrystallised in ethanol to afford the desired product.
N,N0-Di-(4-chlorophenyl)malonamide I: Yield 95%, white solid, m.p. 218–220 8C (reported 217 8C [21]).
N,N0-Di-(4-fluorophenyl)malonamide II: Yield 91%, white solid, m.p. 214–216 8C (reported 212 8C [21]).
Once a mixture of N,N0-di-(4-chlorophenyl)malonamide (0.642 g, 2.0 mmol) and the other time N,N0-di-(4-
fluorophenyl)malonamide (0.576 g, 2.0 mmol) with 5–6 times by weight polyphosphoric acid were stirred in an oil
bath at 140–150 8C for 6 h. Then the mixture was cooled, diluted with water and the resultant gum solidified by
standing over night. The solid was filtered and dried in air. It was recrystallised from ethanol to afford corresponding
hydroxy quinolone as creamy crystals.
1
Compound 1, Yield 82%, m.p. 350 8C (d); FT-IR (KBr): n (cmꢀ1): 3392, 1654, 1600, 1448 and 1116; H NMR
(300 MHz, DMSO-d6): d 5.8 (s, 1H), 7.69 (s, 1H), 7.26 (dd, 1H, J = 8.6, 4.8 Hz), 7.51 (d, 1H, J = 8.6 Hz), 11.35 (NH).
Compound 2, Yield 75%, m.p. 345 8C; FT-IR (KBr): n (cmꢀ1): 3392, 3228, 3085, 1637, 1610, 1514 and 1195; 1H
NMR (300 MHz, DMSO-d6): d 5.77 (s, 1H), 7.27 (dd, 1H, J = 8.9.4.7 Hz), 7.38 (m, 1H), 7.45 (m, 1H), 11.29 (NH).
Diazotization of the aromatic and heteroaromatic amines was affected with nitrosyl sulphuric acid. A typical
procedure that is described below is used for 4-cyanoaniline. The other dyes were prepared in a similar manner. Table 1
shows the characterization data for all of the prepared dyes.
4-Cyanoaniline (0.236 g, 2.0 mmol) was dissolved in a mixture of glacial acetic acid–propionic acid (6 mL, 2:4)
and cooled in an ice-salt bath to ꢀ5 8C. The liquor was then added in portions during 45 min to a cold solution of
nitrosyl sulphuric acid (prepared from sodium nitrite (1 g) and concentrated sulphuric acid (7 mL) at 60 8C). The
mixture was stirred for an additional 45 min at the same temperature. After diazotization was completed the diazo
liquor was added to a vigorously stirring solution of 6-choloro-4-hydroxy-2-quinolone (0.391 g, 2.0 mmol) in sodium
hydroxide (0.4 g, 10 mmol) and water (10 mL). The pH of the reaction mixture was maintained at 10–11 by adding
2.5% sodium hydroxide solution. The mixture was then stirred for 1 h at 0–5 8C. The progress of the reaction was
followed by TLC using ethyl acetate–petroleum benzene (7:3 by volume) as developing solvent and silica gel TLC
plates as the stationary phase. In the end of procedure the pH of reaction mixture was regulated at 5–6 by addition of
10% hydrochloric acid solution. The resulting solid was filtered, washed with cold water and dried. Recrystallization
from DMF gave red crystals (0.6 g, 92%).

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E.O. Moradi-e-Rufchahi / Chinese Chemical Letters 21 (2010) 542–546
Table 1
Characterization data for the synthesized dyes.
Dye
no.
IR (cmꢀ1, KBr)
1H NMR (DMSO-d6)
Elemental analysis
m.p. (8C)
3a
3250, 3051, 2239,
1690, 1600, 1437,
1251
7.89–7.99 (m, overlapped, 5H),
7.21 (d, 1H, J = 9 Hz),
C, 59.17; H, 2.77; Cl, 10.94; N,
17.26; O, 9.86. Found: C, 58.52;
H, 2.71; Cl, 11.02; N, 17.37; O,
10.38%.
335–337
7.67 (d, 1H, J = 9 Hz), 14.81 (OH),
15.20 (NH)
3b
3400, 3200, 3070,
1680, 1602, 1488,
1438
8.31 (d, 2H), 7.82 (overlapped, 3H),
7.19 (1H), 7.65 (d, 1H, J = 7.5 Hz),
11.26 (NH), 11.56 (NH), 14.84 (OH),
15.30 (NH)
C, 52.25; H, 2.61; Cl, 10.30; N,
16.26; O, 18.58. Found: C, 51.95; H,
2.67; Cl, 10.42; N, 16.34; O, 18.62%.
330–331
3c
3446, 3176, 3050,
1635, 1602, 1463,
1193
7.22–8.14 (m, 7H, overlapped),
11. 6 (NH), 15.30 (NH)
C, 53.86; H, 2.52; Cl, 9.96; N, 15.70; O,
8.98; S, 8.98. Found: C, 53.51; H, 2.71; Cl,
10.05; N, 15.96; O, 8.45; S, 9.32%.
C, 61.62; H, 3.14; Cl, 10.13; N, 15.98; O,
9.13. Found: C, 61.90; H, 3.18; Cl, 9.98; N,
15.72; O, 9.22%.
310–312
315–318
3d
3451, 3201, 1685,
1602, 1458
9.05 (dd, 1H), 8.49 (t, 2H),
7.17–8.18 (m, overlapped, 7H),
11.34 (NH), 11.45 (NH),
15.98 (OH), 16.73 (NH)
4a
4b
3467, 3193, 2221,
1680, 1614, 1496
7.92 (d, 2H, J = 8.4 Hz), 7.82 (2H),
7.60 (1H), 7.54 (dt, 1H,
C, 62.34; H, 2.92; F, 6.17; N, 18.18; O,
10.39. Found: C, 62.61; H, 2.99; F, 5.96; N,
17.92; O, 10.52%.
327–328
355
J = 8.5, 2.9 Hz) 7.22 (1H), 11.28 (NH),
11.47 (NH), 14.88 (OH), 15.38 (NH)
8.34 (d, 2H, J = 5 Hz), 7.85 (d, 1H,
J = 5 Hz), 7.92 (d, 1H, J = 5 Hz),
7.64 (q, 1H), 7.56 (d, 1H, J = 5, 1.5 Hz),
7.26 (d, 1H), 10.30 (NH),
3429, 3191, 1687,
1596, 1515, 1342,
1293
C, 54.89; H, 2.74; F, 5.79; N, 17.07; O,
19.51. Found: C, 54.82; H, 2.69; F, 5.84; N,
17.19; O, 19.46%.
11.53 (NH), 14.97 (OH), 15.39 (NH)
8.07 (d, 1H, J = 4.7 Hz), 7.48 (t, 1H),
7.40 (t, 1H), 7.84 (d, 1H, J = 4.7 Hz),
7.65 (dd, 1H, J = 5.2, 1.7 Hz) 7.56 (dt, 1H,
J = 5.1, 1.8 Hz), 11.2 (NH),
4c
3257, 1649, 1481,
1519, 1197
C, 56.47; H, 2.65; F, 5.59; N, 16.47; O,
9.41; S, 9.41. Found: C, 56.62; H, 2.69; F,
5.65; N, 16.17; O, 9.31; S, 9.56%.
298
11.35 (NH) 7.23 (d, 1H), 15.40 (NH)
9.05 (d, 1H, J = 9 Hz), 8.52 (dd, 1H),
7.13–8.19 (m, overlapped, 7H),
11.2 (NH), 11. 3 (NH), 16.04 (OH),
16.76 (NH)
4d
3448, 3068, 1654,
1616, 1436, 1380,
1116
C, 64.67; H, 3.29; F, 5.69; N, 16.77; O,
9.58. Found: C, 64.12; H, 3.11; F, 5.82; N,
17.05; O, 9.90%.
289–291
2. Results and discussion
The heterocyclic azo dyes 3a–3d and 4a–4d were prepared by coupling 6-chloro-4-hydroxy-2-quinolon and 6-fluoro-
4-hydroxy-2-quinolone with diazotized aromatic and heteroaromatic amines (Scheme 2). The dyes may exist in four
possible tautomeric forms named enol-azo-keto (T1), keto-hydrazo-keto (T2), enol-azo-enol (T3) and keto-hydrazo-enol
Scheme 2. Synthetic routes for the preparation of azo dyes 3 (X = Cl) and 4 (X = F).

E.O. Moradi-e-Rufchahi / Chinese Chemical Letters 21 (2010) 542–546
545
Scheme 3. Possible tautomeric forms for the prepared azo dyes.
(T4) (Scheme 3). The infrared spectra of all the dyes (in KBr) showed intense OH and NH bands at 3467–3257 cmꢀ1. The
IR spectra also showed an intense band at 1690–1635 cmꢀ1, which was assigned to amid carbonyl group.
The 1H NMR spectra measured in DMSO-d6 at 25 8C showed a multiplet at 9.05–7.17 for aromatic protons (Aro.-
H). Two attributed broad singlet peaks at 11.60–11.20 and 11.56–11.30 ppm for amide (–NH) groups related to two
types of tautomeric forms T1 and T2. The broad peaks at 16.04–14.81 was assigned to tautomeric enol proton (C C–
OH) and 15.30–16.76 assigned to tautomeric hydrazone proton ( N–NH). These results show that the dyes may exist
as a mixture of tautomeric forms T1 and T2 in DMSO.
The absorption spectra of the prepared dyes were measured in various solvents at a concentration of approximately
10ꢀ6 to 10ꢀ8 mol/L and were run at different concentrations. The dyes were completely soluble in DMSO. Therefore,
more dilute solutions were prepared, and it was found in all cases that lmax was unaffected by the dye concentration.
The stock solutions of each dye were accurately prepared and dilutions of these stocks were used for absorption
measurements. The results are given in Table 2.
The electronic absorption spectral characteristics of the azo compounds in various solvents are given in Table 2. As
it is apparent, the dyes with heterocyclic coupling component resulted in bathochromic shifts in all solvents (e.g. for
dye 4c Dl = 39 nm relative to dye 4a in acetonitrile). The hydroxy quinolone azo dyes which have heteroaromatic
coupling component 2-aminobenzothiazole and 8-aminoquinoline show bathochromic shifts in comparison with
aromatic amines.
It was also observed that the absorption curves of the dyes were a little sensitive to acid or base except dyes 3a, 3d
and 4a. The lmax of those dyes showed hypsochromic shifts when 0.1 mol/L NaOH was added to dye solution in
ethanol. The lmax of the dye 3d in ethanol showed bathochromic shift when 0.1 mol/L HCl was added (Dl = 29 nm).
All of the dyes showed one absorption maxima in basic solutions and DMSO. Consequently the dyes may exist in a
single tautomeric form in these media. Fig. 1 shows the absorption behavior of dye 3a in acidic and basic solutions.
Table 2
Influence of solvent on lmax of dyes 3 and 4.
Dye no.
EtOH/OHꢀ
DMSO
DMF
Acetonitrile
Chloroform
Ethanol
Acetic acid
EtOH/H+
3a
3b
3c
3d
4a
4b
4c
4d
401
424
437
404
399
424
438
445
407
426
428
448
410
424
416
428
404, 426 s
423
402, 395 s
418, 401 s
454
419, 396 s
425, 404 s
440
415, 399 s
422, 402 s
435
424, 401 s
427, 401 s
437
428, 402 s
421, 400 s
434
446
447
440
454
419
442
448
407
403, 397 s
418, 403 s
442
416, 400 s
424, 400 s
437
415, 397 s
421, 405 s
437
421, 399 s
425, 400 s
437
414, 401 s
421, 401 s
433
422
449
430, 465 s
438, 416 s
445, 417 s
436, 447 s
423, 453 s
426, 448 s
s = shoulder.

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E.O. Moradi-e-Rufchahi / Chinese Chemical Letters 21 (2010) 542–546
Fig. 1. Absorption spectra of dye 3a in acidic and basic solutions.
3. Conclusion
In this work 6-chloro-4-hydroxy-2-quinolone 1 and 6-flouro-4-hydroxy-2-quinolone 2 were synthesized from
corresponding dianilides I and II. Afterwards, we prepared eight azo disperse dyes by coupling of two aromatic and
two heteroaromatic amines with those compounds. The dyes were characterized and their absorption behaviors were
studied. The absorption data of the synthesized dyes revealed that some of these compounds exist in equilibrium of
tautomeric species (Scheme 3). The results taken from absorption spectra of prepared dyes also showed bathochromic
shifts for those compounds which have heterocyclic coupling components.
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